(1) Field of the Invention
This invention relates to pulling flexible pipe, cables and the like from wells and more particularly relates to portable derrick hoists therefor.
(2) Description of the Prior Art
Pulling tools or pumps from wells has always presented a problem. Sometimes previously, a permanent derrick is constructed over the well for this purpose. In the western United States for domestic water wells the windmill tower formed this derrick for pulling the pipe or sucker rod from the well.
At other times, a portable tower or derricks in the form of being completely truck mounted have been used.
In recent years, a more and more flexible material has been used in wells. Particularly in domestic water wells, many of the pumps are self-contained submergible pumps which include not only the pump but an electric motor to drive the pump which are located in the bottom of the well attached to a bottom of a flexible pipe. This flexible pipe may be plastic hose or tube with an electric cable strapped to it.
In addition, in the normal service of a well it is often necessary to run cables in the well. These cables sometimes have balers attached to them or have grabs or grapplers or other tools to fish loose material from the well.
Before this application was filed, the applicant caused a search to be made in the United States Patent and Trademark Office. The following patents were found as a result of that search.
U.S. Pat. No. 158,434; Newcomb
U.S. Pat. No. 656,079; Arsnean
U.S. Pat. No. 772,994; Wood
U.S. Pat. No. 932,444; Chambers
U.S. Pat. No. 1,103,823; Padgett
U.S. Pat. No. 1,789,025; Shepard
U.S. Pat. No. 2,222,243; Sandstrom
U.S. Pat. No. 2,643,856; Sales
U.S. Pat. No. 2,648,521; Sales
U.S. Pat. No. 2,676,677; Anderson
U.S. Pat. No. 2,941,634; Hanks
U.S. Pat. No. 2,985,430; Greenwood
U.S. Pat. No. 3,498,472; Rodgers
U.S. Pat. No. 3,991,978; Jones
CHAMBERS discloses a stump puller having a differential hoist. A draft animal is attached to the cable to pull the stump.
NEWCOMB discloses a scaffold over a well with a pulley at the top of the scaffold.
JONES discloses a mast or boom which is attached to to the top of the casing. He then attaches the cable and the winch 29 to raise material from the well.
GREENWOOD discloses a hoist on a well which has telescoping legs.
The remaining patents do not appear to be any more pertinent to this invention than the ones discussed above.